If it isn't kiddie porn or snuff films, then he isn't breaking any laws, and its none of anyone's business.
I might avoid ever having dinner at his house, due to sanitary and hygienic concerns, but it isn't my place to judge his proclivities if he isn't hurting anyone.
As to confronting him about it? Why on earth would you do that?! It's his life. Assuming he's not forcing anyone to fulfill his fantasies, it's nobody's business but his.
FWIW (because I know you're going there in your mind :-) ), I don't care for porn. Never have. It's not the moral issue as much as not seeing much potential for pleasure in watching other people copulate. If I wanna get 'stimulated' all I have to do is go to the gym for an hour and watch my female contemporaries work out. :->
If he hasn't actually broken any laws then that's a waste of resources, man power and tax payer dollars.
If it isn't kiddie porn or snuff films, then he isn't breaking any laws, and its none of anyone's business.
I might avoid ever having dinner at his house, due to sanitary and hygienic concerns, but it isn't my place to judge his proclivities if he isn't hurting anyone.
There Probably Already Are.
It's not the people who are open about their "perversions" that you should be concerned about; it's what all those 'decent, nice normal' people are hiding in their closets and little locked boxes that should concern you.